Structural panel forming machine and method



Filed Feb. 5. 194s Sept. 26, 1950 v c. c. sAcHs 2,523,525

smuc'rum. PANEL Foaumc MACHINE AND mamon m kP/Pa d 57m/9,

D INVENTOR.

` c. c. sAcHs STRUCTURAL. PANEL. Forums MACHINE AND mon Filed Feb. '5, 194s Y sgpx. 26, 195o 4 Sheets-Sheet 2 @kwam 1N VEN TOR.

BY /f/ rraRA/f/ Sept. 26, 1950 c. c. sAcHs smcmn. PANEL Forum uAcHmE mn mamon 4 Sheets-Sheet 3 Filed Feb. 5;, 1948 INVENTOR.

Sept. 26, 1950 c. c. sAcHs sTRuc'rURAL PANEL FoRMING MACHINE ma METHOD 4 VSheets-Sheet 4 Filed Feb. 5, 1948 BY @zum Patented Sept. 26, 1950 STRUCTURAL PANEL FGRMING MACHINE AND METHOD Carrol C. Sachs, North Hollywood, Galif.,` assignor to Alexander H. Kerr & Co., Inc., Los Angeles,

Calif.

VApplication February 5, 1948, Serial No. 6,520

This invention has relation to a device for producing structural panels and refers particularly to the type of device disclosed in my copending application, Serial No. 768,777, filed on August l5, 1947.

In the 'device of the invention, groups of forms are placed between plates and sheets of material are laid about and between these forms while still in plastic state. The plates are thereupon adjusted to apply pressure to the covered forms, whereupon heat is applied to the plates and to the forms for the purpose of curing the material as required in order to produce a homogenous, one-piece, load-bearing panel.

It is an object of the invention to provide improved means for supporting and operating the groups of forms used in the machine for the purpose of molding the panel of the invention.

It is a. further object to provide improved means for heating these forms and the plates between which they are placed.

Other objects and the many advantageous features ofthe invention will appear upon perusal of the following detailed description thereof and reference is invited to the accompanying drawings in which a preferred form of the invention is illustrated.

In the drawings:

Fig. 1 is a plan view illustrating the essential feature of 'my invention;

Fig. 2 is a substantially corresponding end view of the device with the parts at the left side thereof broken away for lack of spa'ce;

Fig. 3 shows, on a larger scale, the parts'at the right end of Fig. 2, in a different position of adjustment and partly in section in order to disclose important interior mechanisms;

Fig. 4 is a detail View showing elements of.

Fig. 3 in a diierent position of adjustment;

Fig. 5 is a. plan view of the mechanism shown in Fig. 3 with parts thereof broken away for the sake of clearness; l

Fig. 6 is a sectional view of portions of Fig. 2, on a larger scale; Y

Figs. 7, 8 and 9 are detail views of elements of venient manner.

19 claims. (01.,154-15 2 of the device. The upper platen 3 is supported for vertical movement relative to the lower platen by hydraulic means including cylinders 5 fitted with pistons 6 and the rods 1 extending from these pistons are secured to the base I in any con- Conduits 8 lead from these pistons to a source of a fluid under pressure for p the purpose of elevating the upper platen into the position substantially as indicated in Fig. 2. A valve 9 is placed in each conduit and it is operable to admit pressure uid to the cylinders for the purpose of elevating the upper platen and movable into a second position to open an exhaust passage for the fluid thereby, by gravity, to urge return movement of the platen.

Along the side-edges of the upper platen t' are secured channelled beams IIl, I I combining to form a track for a carriage I2 which, when the platen 3 is in its elevated position, is movable along the underside of this platen for the purpose which will be described presently, Any suitable mechanism may be employed for reciprocating this carriage under the platen and such mechanism is in Fig. 2, for the sake of simplicity, shown to include a motor I3 which is mounted on the carriage and by elements such as a sprock- V et chain I4 extending from a sprocket wheel It of the motor shaft to a wheel It of one of the rollers Il.

The numerals 20, 2I indicate. generally, forms which aremounted at each side of the above described platen combination for reclprocatory movement into and out ofV thiscombination. These forms include each a series of bars 2-2, 23 which, as best indicated in Fig. 8, are shaped to produce the wall panel which the device of the present invention is constructed to form. The bars are all alike but, as indicated in this drawing, are alternately reversed. Except for this alternate reversal of the ba'rs, the forms on both sides of the device may be exactly alike and reason, equally to the form on the other side of the machine. All of these bars are, for the sake the device the importance of which is hereinafter fully set forth; and

Fig. 10 is an enlarged fragmentary perspective view showing an end of a mandrel supported by a manifold `support bar.

' On a base. l is mounted a rectangular plate 2 and a similar plate 3 is held supported above the plate 2 in verticalalignment therewith. The two plates are for convenience lhereinafter generally referred toas the upper and lower platens of the simplicity of description, hereinafter generally referred to as the mandrels ofthe machine and each assembly of mandrels is referred to as a manifold.

Referring now to Figs.' 3 to 6 of the drawings, a post 25 is secured to the base I and it projects laterally therefrom. A carriage v26 is mounted on this post for longitudinal sliding movement thereon by means of a gear wheel 2l engaging a rack 28 which is secured to or cut into the underside of the post. A bracket 29 rises from this carriage to support a sub-carriage 30 which is pivotally hung thereon, as indicated at 3|. This sub-carriage is shown bifurcated to straddle the bracket 29 and it is important to note that the inner ends thereof are rigidly secured to the side surface of a cross head 35. The latter is in such manner supported for vertical swinging movement on the carriage 26.

. A shank 32 extends from the cross head 35 adjacent the post 25 and, in the position indicated in Figs. 3 and 5, parallel therewith. A groove 36 is sunk into the opposite side surface of the cross head of a size to receive a rectangular member 31 which is shaped to i-lt tightly within this groove and it is shown clamped in position therein by means of screws 38, see Fig. 6. It is noticed that a recess is sunk into the bottom of the groove to provide an enclosed space 40 extending nearly the full length of the cross head. The inner ends of the mandrels 22 are. as best shown in Fig. 7, machined to provide cylindrical shanks 44 which fit tightly in and are held rigidly within perforations 42 of a manifold support bar 4I, and a rectangular groove 43 is sunk into the opposite side edge of the bar, see also Fig. 10. This groove is of a size to seat tightly on t-he member 31, to which the bar is secured in any convenient manner. In order to provide a tight joint, it may be found advisable to place steam gaskets 39 between the side edges of the bar 4I and the shoulders of the member 36. As best shown in Figs. 6 and 10, a cylindrical bore 45 extends through each of the mandrels and the end of this bore is shown closed by means of a plate 46. It is also important to note that a tubular member 41 is seated in the member 31 and that it extends axially through the mandrel nearly to the above named end plate 46, there being one member 41 within each mandrel.

A conduit 56 communicates with the chamber 40 of the cross head and a second conduit 5I concharge outlet. The aforenamed tank combination is for the sake of simplicity hereinafter generally referred to as the impregnator of the nects with the space within the groove31'l of the member 31. These conduits are provided for the purpose of carrying steam to heat the mandrels and the conduit is for this purpose connected with a steam boiler of any suitable commercially well known construction (not shown). The conduit 5| forms a discharge outlet for steam which, from the conduit 50 flows through the chamber 40, the tubes 41 and returns through the space 45 surrounding the tube 41 finally to discharge through the conduit 5I. Suitable valves 52 and 53 are provided in these conduits for the purpose of controlling the flow of steam through the mandrels.

In order to fabricate the structural unit for the production of which the device of the present invention is designed, the following steps are required. It becomes necessary in the first instance to deposit a layer or web of plastic mate-a rial in the form of a resin which is capable of polymerization runder thel inuence of heat. l shall now for the sake of clearness describe simple means of feeding such web of material on to the plate 2, but wish it understood that, in actual practice, to suit varying conditions, more complete devices may be required for this purpose..

A tank 55 is shown secured within the carriage I2, see also Fig. 9, and the resinous composition held stored within this tank is discharged through a spout 56. )A lever 51 is -shown pivotally hung on the tank and it is tted with a plate 58 which, when the lever is in the position shown in Fig. 9, forms a closure for the disdevice.

The motor I3 is now started to advance the carriage, with the impregnator, through the space between the plates 2, 3, the operator at the same time raising the lever 51 to allow the composition from the tank to settle on the plate 2 in the form of a web 60, whereupon the lever again is' dropped to close the discharge outlet and so as to sever the web from the body of the composition. But the movement of the carriage is continued until the opposite end of the track is reached.

The next step in the molding of the unit consists in advancing the manifold 20 transversely into position between the two plates, directly above the web deposited on the lower plate. This movement is, as above pointed out, effected through the medium of the gear wheel 21. 'I'he latter is, for this purpose, connected for rotation by an electric motor 54. It is noticed that the manifold, in the position shown in Fig. 2, is held slightly upwardly tilted. This is done in order to assure clearance above the web on the plate 2 during the advance movement of' the manifold. The latter is, however, lowered into horizontal position on top of the web as it reaches registration therewith in the manner which will be described. presently.

Once the manifold 20 has been placed on top V of the web 60. it is required to return the carriage I2 to its initial position, at the same time raising the lever 51 of the impregnator to cause a second web 6I to settle over and into the spaces between the mandrels 22. The lever is then again moved to out off the supply from the impregnator.

It was above stated that the two manifolds may be exactly alike except for the relative reversal of the mandrels. It follows that the manifold 2| now may be advanced into t-he space above the newly laid web 6| in exactly the same manner as above described, whereupon the carriage |2 again is advanced to place a third web 62 on top ofthe intertted manifolds and the portions of the web 62 appearing on top thereof, see Fig. 8. The valves 9 are thereupon opened and the combined weight of the upper plate 3 and the carriage I2 causes these parts to sink until the upper plate settles firmly on the web covered manifolds.

It was above stated that conduits 50 and 5| are provided for carrying steam through the manifolds. It is furthermore to be noted that similar conduits 66, 61 are provided to circulate steam through the platens 2, 3. As the ow through the manifold conduits is controlled by the valves 52, 53 so are'valves 68, 69 provided to control the flow through the platens. All of these valves are now opened to cause the flow of steam pass- -ing through the platens and the manifolds to heat these devices as required for the polymerization of the resinous webs which, when completely polymerized, form the homogeneous panel lof the invention. After the panel has been completed, it is merely required to withdraw the manifolds therefrom, and this is done by startproject from this plate to bear against the side edges of the platens 2. 3. These posts are provided for the purpose of preventing movement of the sleeve toward the platens. The sleeve is formed with a worm gear 1| in permanent mesh with a worm 12 and the latter is rigidly secured to the shaft 13 of a motor il. When this motor is started it is` to be noted that, because the sleeve is held against movement toward the platens, it exerts, through the aforenamed worm gear connection, a powerful pull on the shank 32, at very slow speed, to dislodge the manifold. It is to be understood, of course, that the mechanisms are operated simultaneously to dislodge both manifolds. It is further to be noted that bars 80, 8| are secured to the platens along the edges thereof and that these bars are grooved substantially as indicated at 18, 19 to form along the inner edges thereof ridges 82, 83. 'I'he polymerized webs of the finished panel abut the sides of the ridges 82, 83 and so are held firmly in position during the initial withdrawal of the manifolds. It is also important to no1-.e that any web material which may have overflowed the edges of the finished panel will be cut olf by the sharp ridges'for subsequent manual removal.

to start the motor 54`quickly to return the manifolds to the initial position indicated in Fig. 2.

It was above stated that the sub-carriage 30 is pivotally supported on the carriage member 29 and it is swung on the pivot 3| into the tilted position of Fig. 2 in the following` manner. A stem d5 is seated for rotation in the sub-carriage t@ and` it is fitted with a cam t6 which rides against a ledge tl of the carriage bracket 20.

' An arm da is rigidly secured to one end of the stem i3d, from which it projects downwardly and the manifolds. The rear end of the post is shown anchored in a standard 90 of the machine base. A bracket 9| rises from this standard into the pathof movement of the arm'88 to cause the arm to swing into the forwardly inclined position of Fig. 2 at the end of the retractive movement. The cam @E is, during this cam rotating movement, caused to rise against the ledge 8l of the bracket 30 and so to swing'the manifold into the tilted position of Fig. 2.

After the fnished panel has been removed from1th`e machine, the motors 54- and 'lll` are started to return the manifolds, one by one, to their advanced `positions, in the order above described. At the end of this advance movement, it is found that the arm 88 of each manifold strikes a fixed stop 02 of the machine base thereby to' release the manifold for movement into the horizontal position of Fig. 3.

In the drawings, the manifolds are, for the sake of simplicity, shown supported on the single carriage units hereinbefore described. When such single supports are employed, it becomes necessary to provide means for preventing rotative movement of each manifold on its shank 32 and each carriage on its post 25. Illustrative of Upon completion of this powerful l initial dislodging movement, it is merely required ,rearwardly during the retractive movement of ananas simple means of checking such rocking movement I have, in Fig. `3, shown a feather key 03 of the carriage member 28 engaging an axial slot 94 of the post. Similarly, a feather .key 8l of the member 30 is fitted to ride in a slot 08 of the shank 32. For the purpose of preventing rotation of the motor assembly on the shank 32, I have shown a feather key 91 of the motor support. 98 riding in the slot 96 of the shank 32. In actual practice, however, I prefer to provide more substantial supports including two such supporting devices for each manifold, including posts 25 placed in transverse parallel spaced relation to each other and Shanks 32 riding in the carriages on these posts.

It was above stated that the plate 11, carrying the posts 16, is tied to the sleeve 10. Itis noticed. however, that whereas the sleeve is mounted for rotation on the screw threads of the shank 32, it isnecessary to provide means for maintaining the plate non-rotatable on the shank. A feather key |00 is, for this purpose shown seated in the -slot of the shanks and it rides in a slot |0| of iently be placed between the plate and the flange' |03, as indicatedin Fig. 5.

It is essential for the proper operation of the device of my invention that the-two manifolds become correctly seated between theplatens and interlocked when so positioned to the end that no variation in the spacings between the mandrels of the manifolds mayV occur. For this purpose I have shown the end plates l0 of the mandrels outwardly projected at |05 to ride in sockets |06 of the cross heads inserts 31. One of these sockets is shown in Fig. 1 in alignment with the end plate projection |01 of the mandrel 22 at the opposite side of the base. Y

I claim: f

l. In a machine for forming panels from a moldable polymerizable compound, a base, plat-A ens supported on said base for vertical movement relative to each other, carriages supported by said base, a series of parallel equidistantly spaced mandrels supported by each carriage, means for moving said carriages on the base to cause said mandrels to move into and out of the space between said platens, a dispensing device for said compound, and means for moving'said device back and forth through the space between the platens a't right angles to the movement ofthe mandrels. the device being manualy operable to deposit layers of the compound on the lower platens and on the mandrels as they reach fully advanced position within the space between the platens.

2. In a machine for forming panels from a moldable polymerizable compound, a base. a plat- Aen on said base, a second platen supported by said base, means for adjusting said second platen vertically relative to the first platen, carriages supported by said base, a series of parallel equidistantly spaced mandrels supported by each 1 carriage, means for moving said carriages on the base to cause said mandrels to move into and on the lower platens and on the mandrels as they reach fully advanced position within the space between the platens.

3. In a machine for forming panels from a moldablel polymerizable compound, a base. platand on the mandrels as they reach fully advanced position within the space between the platens,

parallel equidistantly spaced mandrels supported by each carriage, means for moving said carriages on the base to cause said mandrels to move into and out of the space between said platens, the mandrels of yone series being so aligned relative to the mandrels of thev other series that the mandrels of one substantialh' occupy the spaces between the mandrels of the other, when `fully advanced into the space between the platens, a dispensingdevice for said compound. and means for moving said device back and forth through the space between the platens at right angles to the movement of the mandrels, the device being manually operable to deposit layers of the compound on the lower platens and on the mandrels as they reach position within the space between the platens.

4. In a panel forming machine, a lower platen on said base, an upper platten supported by the base in spaced relation` to said' lower platen, means for adjusting said upper platen vertically relative to the lower platen, carriages supported by said base, a series of parallel equidistantly spaced mandrels supported by each carriage, means for moving said carriages on the base to cause said mandrels to move into and out of the space between said platens, a track on said upper platen, a compound dispensing device on said track. means for moving said device back and forth on said track through the space between the platens at right angles to the mandrel movement. the device being manually operable to deposit layers of the compound on the lower platen and on the mandrels as theyreach fully and means for heating said platens and the said mandrels to cure the layers of compound deposited therebetween.

7. In a machine for forming panels from a moldable polymerizable compound, a base, platens supported on said base for vertical movement relative to each other, supports projecting from said .base in opposite directions and in continued axial alignment, carriages seated on said supports, a series of parallel equidistantly spaced mandrels supported by each carriage. means for moving said carriages on the said supports to cause the mandrels to move completely into and subsequently out of the space between the platens, a dispensing device for said compound, and means for moving said device back and forth through the space between the platens at right angles to the movement of the mandrels, the device being manually operable to deposit layers of the compound on the lower platens and on the mandrels as they reach position within the space between the platens.

8. In a machine for forming panelsffrom a moldable polymerizable compound, a base, platens supported on said base for vertical movement relative to each other, carriages supported by said base, a sub-carriage on each carriage, a, series of parallel equidistantly spaced mandrels held on each sub-carriage with the inner ends thereof slightly upwardly tilted, means for movmg said carriages horizontally on the base to cause said mandrels to move into and out of the space between the platens, means yfor releasing the mandrels for movement into horizontal position within the platens, a dispensing device 'for said compound, means for moving said deadvanced, position within the space between the platens.

5. In a machine for forming panels from a moldable polymerizable compound, a base, platens supported on said base for vertical movement relative to each other, carriages supported by said base, a series of parallel equidistantly spaced mandrels supported by each carriage, means for moving said carriages on the base to cause said mandrels to move into and out of the space between said platens, a dispensing device for said compound, means for moving said device back and forth through the space between the platens at right angles to the movement of the mandrels, and means for heating saidy platens and the said mandrels to cure the layers of compound deposited therebetween.

6. In a panel forming machine, a lower platen on said base. an upper platen supported bythe base in spaced relation to said lower platen, means for adjusting said upper platen vertically relative to the lower platen, carriages supported by said base, a series of parallel equidistantly spaced mandrels supported by each carriage, means for moving said carriages on the base to cause said mandrels to move into and out of the space between said platens, a track on said upper platen, a compound dispensing device on said track, means for moving said device back and forth on said track through the space between the platens at right angles to the mandrel movement, the device beingmanually operable to deposit layers of the compound on the lower platen the platens at right angles to the movement of the mandrels, the device being manually operable to deposit layers of the compound on 'the lower platens and on the mandrels as they reach position within the space between the platens,

- and means for returning the mandrels to the upwardly tilted position at the end of their outward movement.

9. In a machine for forming panels from a moldable polymerizable compound, a base, platens supported on saidbase for vertical movement relative to each other, carriages supported by said base, a series of parallel equidistantly spaced mandrels supported by each carriage with their free ends directed toward said platens and being slightly tapered toward their free ends, means for moving said carriages on the base to cause said mandrels to move into and out of the space between said platens, a dispensing device for said compound, and means for moving said device back and forth through the space between the platens at right angles to the movement of the mandrels, the device beingmanually operable to deposit layers of the compound on the lower platens and on the mandrels a's they reach position within the' spacebetween the platens.

10. Ina panel forming machine, a base, platens supported on said base for vertical movement relative to each other, supports projecting from said base in Opposite directions and in continued axial alignment, carriages onsaid sup-V a manifold on each carriage including mandrels `extending inwardly toward the base, support members extending from said manifold in the opposite direction, sub-carriages on said support members, posts inwardlyprojecting from said manifolds for contact with said platens, meansV on said sub-carriages for movingthe rotative movement of vsaid carriages, sub-carriages andi manifolds on their supports.

14. Ina` panel forming machine, a base, platens supported on said base for vertical movement latter relative to their support members, contact of the posts with the platens preventing movement of the sub-carriages toward the platens and inducing movement of the support members to start withdrawal-movement of the manifolds.

` 1l. In a panel forming machine, a base, platens relative to each other, posts horizontally extending from the sides of said base in opposite direction and in axially parallel relation to each other, carriages mounted for axial movement on said posts, racks on the posts, gear wheels in the carriages in mesh with said racks, a prime mover v for rotating each gear wheel to impart reciprobefore they move into the space between the Y platens, support members extending from said manifolds in the opposite direction, sub-carriages on said support members, posts inwardly projecting from 'said manifolds for ncontact with said platens, means on said sub-carriages for moving the latter relative to their support members, contact of the posts with the platens preventing movement of thev sub-carriages' toward the platens and inducing movement'of the supcatory movement to said carriages, a manifold l mounted on each carriage for vertical swinging. movement thereon, each carriage including' aIV series of parallel equidistantly spaced mandrels inwardly extending. said mandrels being slightly tapered toward their free inner ends and slightly upwardly tilted, movement of the carriages causing the mandrels to enter into the space between said platens, and means for releasing said mandrels for movement into horizontal position within said space.

15. In a panel forming machine, a base, platens supported on said base for vertical movement relative to each other, posts horizontally extending from the sides of saidbase in opposite direc- Y tion and in axially parallel relation to each other,

port members to start withdrawal movement of the manifolds.

l2, In a machinefor forming panels from a moldable polymerizable compound, al base, platens supported on said base for vertical movement relative to each other, carriages-supported by said base, a series of parallel equidistantly `spaced mandrels supported by each carriage,

means for movingsaid carriages on the base to cause said mandrels to move into and out of -the space between said platens, a dispensing device for said compound, and means for moving said device back and forth through the space between the platens at right angles to the movement of the mandrels, the Jdevice being manually operable to deposit layers of the compound lou the lower platens and on the mandrels as they reach position within the space between the platens,

said mandrels being frusto-pyramidal in cross section, the mandrels of one series being inverted relative to the mandrels of the other series to coincide with the sloping sides of the other series when the mandrels reachfully advanced posi-- tion within the space between the platens.

i3. In afpanel forming machine, a base, platens supported on said base for vertical movement relative to each othersupports projecting from said base in opposite directions and in continued axial alignment, carriages on said supports, means for reciprocating said carriages on their supports toward and away from the base,'a manifold on each carriage including mandrels extending inwardly toward the base, support members extending from said manifold in the opposite direction, sub-carriages on said support members, posts inwardly projecting from said manifolds for contact with said platens, means on said subcarriages for moving the latter relative to their support members, contact of the posts with'the platens preventing movement of the sub-carriages toward the platens and inducing movement of the support members to start withdrawal movement of the manifolds, and means for preventing carriages mounted for axial movement on said posts, racks on the posts, gear wheels in the carriages in mesh with said racks, a prime mover for rotating each gear wheel to impart reciprocatory movement to said carriages, a manifold mounted. on eachcarriage for vertical swinging movement thereon, each-carriage including a series of parallel equidistantly spacedmandrels inwardly extending, said mandrels being sligthly tapered toward their free inner ends and slightly upwardly tilted, movement of the carriages causing the mandrels to enter into the space between said platens, means for releasing said mandrels for movement into horizontal position within said space, and means for heating 'said mandrels and tural panelwhich comprises the steps of depositing a first layer of moldable material on a platen, moving an assembly of uniformly spaced man.

drels into contact with the layer deposited on the platen, depositing a second layer of material over and into the spaces between the mandrels, moving a second assembly of mandrels into the spaces between the mandrels of the first assembly and onto the second layer of material, depositing a third layer of material over said second assembly `of mandrels and over the exposer surface of said second layer of material, lowering a second platen onto said third layer of material to press the second assembly of mandrels into the spaces between the mandrels of the first assembly and so to complete the shaping of the second layer of material, and heating the platens and the mandrels to provide an integral panel.

17. The method of producing a hollow structural panel which comprises the steps of depositinto the spaces between the mandrels of the :first assembly, depositing a third layer of material directly on said second assembly of mandrels and on the lexposed surface of said second layer of material, lowering a. second platen onto said third layer of material to press the second assembly of mandrels into the spaces between the mandrels f of the first assembly and so to complete the shaping of the second layer of material, heating the platens and the mandrels of said assemblies to raise the temperature of the webs to provide a one-piece panel, withdrawing the mandrels from the panel, and elevating the second platen to release the panel. v

18. The method of producing a hollow structural panel which comprises the steps of placing a first layer of material upon a platen, moving a, ilrst set of spaced mandrels over and out of contact with said first layer of material, lowering said ilrst set of mandrels into contact with said first layer of material, placing a second layer of material over said rst set of lowered mandrels and in the spaces between said mandrels, moving a second set of spaced mandrels over said second layer of material and out of contact with said second layer, lowering said second set of mandrels into the spaces between the mandrels of said first set and onto said second layer of material, placing a third layer of material over the first and second sets of mandrels, applying a second platen to the top of said third layer of material, causing said platens-to be urged one toward the other, and heating said mandrels and said platens to cause said material to form an integral panel.

19. The method of producing a hollow structural panel which comprises placing a first layer of material on a platen, moving a irst manifold havinga plurality of spaced mandrels over and out of contact with said first layer, lowering said first manifold and mandrels into contact with 35 said ilrst layer, placing a second layer of material over said lowered mandrels and in the spaces between the mandrels on said ilrst manifold, moving a second manifold having a plurality of spaced mandrels over the spaces between the mandrels between said mandrels of said first manifold .and over said second layer, out of contact with said second layer, lowering said mandrels of said second manifold onto said second layer, depositing a third layer of material over the mandrels, applying a second platen to the top of said third layer of material, causing said second platen to be urged toward said rst platen, heating said mandrels and said platens to cause said material to form an integral panel, and removing said mandrels from said panel.

CARROL C. SACHS.

REFERENCES CITED The following references are of record in the file of this patent:

A UNITED STATES PATENTS Number 

